Rock wool and other curiosities - March 10, 2012

What cvan I say? I've been working long hours and now I'm on vacation. It's been not vvery wintry in Minnesota, and decidedly spring here in DC, where I am now. There are a few things I wanted to look at beefore the season is over and I offficially look at spring and wetneess. The first one is rock wool. I had never heard of rock wool unil I began looking into home insulation. Rock wool is, well, Wikipedia sums it up:

Mineral wool, mineral fibers or man-made mineral fibers are fibers made from natural or synthetic minerals or metal oxides. The latter term is generally used to refer solely to synthetic materials including fiberglass, ceramic fibers and stone wool. Industrial applications of mineral wool include thermal insulation (as both structural insulation and pipe insulation), filtration, soundproofing, and germination of seedlings.

Rock wool, the wikipedia article claims, was first manufactured in 1871 in Germany. The idea of insulating buildings using materials that slowed heat loss, as opposaed to just making the wal draft-proof, seems to have been a late one. It really onlly makes sense with timber-frame housing, which has airspace between the insside and outside walls. With older homes (like ours—1890) it makes the most sense to fill the walls with lose cellulose. These days the cellulose is made of treated (fire retardance and mold resistance) ground-up newspaper. But apparently use of cellulose has a long history: straw, corncobs, sawdust, all were used historically. What's amazing to me is that is took so long to make this kind of thing the norm. Energy costs aside, insulated walls are just warmer and less drafty in winter, and keep the house cooler in summer. Our house anyway. But you don't get the sense that this kind of thing ever even occurred to the Ingalls family almost freezing to death on the South Dakota frontier. Rock wool. I don't know that I'd ever head of the stuff beffore. Fiberglass, yes, but somehow meltiing glass and extruding little wisps of glass fibers seems more commonplace than doing the same with rocks. People blow glass... From the little I've read, Scandinavia seems to have been a hotbbed for both fiberglas and rock wool. Lots of market there for insulation. More reseach required.